Frequently, particularly in geographical areas where electric power is needed but not readily available, electric energy is generated by a photovoltaic cell array (i.e., a solar cell) and stored in a battery or other rechargeable electrical storage device. Specifically, the photovoltaic cell array generates an electric current that is electrically coupled to the battery. The current is converted into stored electrical energy in the battery, and the battery thus becomes charged. In some instances, the energy stored in the battery is converted by an inverter to a variable-frequency supply voltage which, in turn, drives a load such as an electric motor which may, for example, be connected to a pump.
To increase the efficiency of the charging process, a regulator is often coupled between the photovoltaic cell array and the battery to regulate the current delivered to the battery by the photovoltaic cell array. However, prior-art regulators either have failed to achieve a satisfactory level of charging efficiency, or have been too expensive to be practical for use in typical solar-powered battery-charging applications.